Climate Variability In The Equatorial Pacific Ocean Induced By Interannual To Interdecadal Variability Of Mixing Coefficient

Diapycnal mixing process, which control Meridional overturning circulation and polarward heat transport in the oceans, plays a vitally important role in global climate and climate change. Since it is sustained by the wind and tide energy input to the oceans, diapycnal mixing coefficient (DMC) will vary along with the change of external energy input. Recent studies showed that the wind energy input to the global oceans has changed greatly interannually to interdecadally over the past decades, so it will be naturally that the DMC in the oceans would has a great change correspondingly.In view of interannual to interdecadal variability of wind energy input, climate variability in the equatorial Pacific Ocean induced by interannual to interdecadal variability of DMC has been examined. The Hallberg Isopycnal Model (HIM) has been used in this study. HIM is an Oceanic General Circulation Model (OGCM) based on the isopycnal coordinate, whose advantage is that it can effectively avoid artificial diapycnal mixing associated with the horizontal mixing/advection in the z-coordinate model. The model domain covers the equatorial Pacific between 30 o S and 30 o N. In the numerical experiments of this study, DMC oscillates periodically either in the whole model domain or in part of the domain. Moreover, the experiments that both wind and DMC oscillate periodically in the domain are also run.As DMC oscillates periodically, both surface temperature and current system are forced into periodic changes in these experiments, in which the most outstanding one is sea surface temperature anomaly (SSTA) in the central and eastern equatorial Pacific, especially in Nino3 region (5 o S~5 o N, 150 oW ~90 oW ). Nino3 SSTA is in...